feat(remotion): Instagram channel-promo template + taste system + design-quality kit

The reference-round workflow, run end to end for a real template:

Taste system (how we learn the user's taste, persisted):
- references/TASTE_PROFILE.md (living design contract) + references/README.md (the
  daily loop) + a "reference round" stage in docs/TEMPLATE_BRIEF.md (provide refs or
  I suggest+mock directions).

Design-quality before/after:
- HeroDemo — the fix recipe vs the faint default: layered-depth background, a proper
  big video type scale, and a bold composed focal object. (Backgrounds were naked,
  text too small, scenes had no objects.)
- YaldaSofreh3D + IGPromoDirections + IGProfileMock — reference-match proofs
  (low-poly 3D, 3 IG-promo style directions, the realistic IG-light page).

Instagram channel-promo template (the deliverable — a flexible 5-scene FlexStory):
- igkit + 5 blocks: IGIntro, IGProfile (realistic IG-light profile, scales to all
  aspects), IGFeed (post grid), IGStats (animated count-up), IGFollowCTA (Follow taps
  to "Following").
- FlexStory gains a `finish` toggle so the IG-light scenes render clean (no brand
  grade). INSTAGRAM_PROMO preset + 3 aspect comps in Root.

Verified: a still of every scene at 9:16 renders clean; full preview MP4 rendering.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

services/remotion/src/scenes/registry.ts

@@ -12,6 +12,11 @@ import { StompBlock } from "./blocks/Stomp";
 import { DeviceMockupBlock } from "./blocks/DeviceMockup";
 import { ProductShowcaseBlock } from "./blocks/ProductShowcase";
 import { PaperCutBlock } from "./blocks/PaperCut";
+import { IGIntroBlock } from "./blocks/IGIntro";
+import { IGProfileBlock } from "./blocks/IGProfile";
+import { IGFeedBlock } from "./blocks/IGFeed";
+import { IGStatsBlock } from "./blocks/IGStats";
+import { IGFollowCTABlock } from "./blocks/IGFollowCTA";
 
 /**
  * The scene-block registry. A FlexStory template is an ordered list of these
@@ -32,6 +37,11 @@ export const SCENE_BLOCKS: Record<string, SceneBlock> = {
   [StompBlock.id]: StompBlock,
   [DeviceMockupBlock.id]: DeviceMockupBlock,
   [PaperCutBlock.id]: PaperCutBlock,
+  [IGIntroBlock.id]: IGIntroBlock,
+  [IGProfileBlock.id]: IGProfileBlock,
+  [IGFeedBlock.id]: IGFeedBlock,
+  [IGStatsBlock.id]: IGStatsBlock,
+  [IGFollowCTABlock.id]: IGFollowCTABlock,
 };
 
 export const BLOCK_LIST = Object.values(SCENE_BLOCKS);